Signaling system



May 2z, 1928. 1,670,461 G. A. LocKE SIGNALING SYSTEM med July 19, 192e 4sheets-sheet 1 u F D-MHIIHI' Y w1 I l l l l l l D i n: G l "i' l 3 D l ss .D da D HJ ID .Q -J '"5 l ll lr l l l l l l l l g sf, E l u l M Q 1 l\l I RQ @11 l 3. l 1 lq N l N g /m/emd/ Gew/7a 0f/fe May 22, 1928.1,670,461

G. A. LocKE S IGNALI NG SYSTEM Filed July 19, 1926 4 Sheets-Sheet 2RECEIVING PIER .sauva NG. DlsTnlBuTr-:R

5TOR| NG Raums RECEIVING DISTRIBUTER May 22, 1928. 1,670,461

G. A. LOCKE SIGNALING SYSTEM Filed July 19, 1926 4 Sheets-Sheet 5 SEN DIN Gr DISTRIBUTER 67 MPuLsa .520

RECEI VIN DISTRIEUTE` PRINTE by 4W Patented May 22, 1928.

UNITED STATES 1,570,461 PATENT OFFICE.

GEORGE AQLOCKE, OF GLEN COVE, NEW YORK, ASSIGNOR T BELL TELEPHONE LAB-ORATORIES, INCORPORATED, 0F NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SIGNALING SYSTEM.

Application med July 19,

This invention relates to signaling systems and more particularly toprinting telegraph systems employing long submarine cables.

Its rincipal object is toy improve the metho and means for synchronizingthe transmitting and receiving mechanisms in p systems of this type.

In ymultiplex operation of printing telegraph systms, as at presentemployed, mechanisms ,are usedI that enable a number of separateprinting telegraph systems at both'ends of the line or cable to beconstated intervals in order to handle traiiic in both directions overone cable. This reversal of direction of transmission in'present typesof systems is generally effected by direction control apparatus operatedautomatically after having been once set to the desired proportions oftime.

It is well known in the art how the mecht anisms for transmitting andreceiving may consist of so-called distributors comprising transmittingrings, receiving rings, and correcting rings. The correcting rings ateach station being used for maintaining synchronism between thedistributor at that end of the cable and the signals transmitted fromthe opposite end of the cable.

' The present invention is applicable to systems of this generalcharacter and comprises means including the correcting ring of thedistributor at one end of the cable orientable in relation to theassociated transmitting ring whereby the system may be adjusted, beforethe actual transmission of messages begins, to maintainsynchronismduring successive reversals of the direction of transmission.By this means different amounts of time lag due to the transmissioncharacteristic of the cable may be compensated for and the tendency onthe part of the sending and receiving distributors to fall out ofsynchronism, during the intervals when the reversals of direction oftransmission take place, is overcome.

This invention has been illustrated in the accompanying drawings inconnection with 1928. Serial No. 123,328.

a multiplex printing telegraph system which includes a terminal station,a land line, a repeater station, a submarine cable, and another terminalstation in series. Fig. 1 represents one terminalstation with itstransmitting and receiving equipment indicated in a schematic form andthe speed correcting mechanism shown in detail. Fig. 2 represcnts therepeater station connected to the land line from thc-station shown inFig. 1 and to the submarine cable leading to the terminal station shownin Fig. 3. Fig. 3 shows in schematic form the transmitting and receivingequipment at the terminal station connected to the submarine cableincoming from the repeater station. The correcting mechanism in thisfigure is shown in detail.

As the invention relates principally to a method and means forsynchronizing the operations of the distributors at the variousstations, such parts of the system as are not directly concerned withthis problem have been shown in a highly schematic form. On the otherhand, the speed correcting or synchronizing means at the terminalstations have been shown in considerable detail.

The various parts of the system are arranged as follows: At the terminalstation A, a transmitting distributor 1 with its associated impulsetransmitting device 2 and a receiving distributor 3 with its printingdevices 4. are shown connected to contacts actuated by cam 5 which,under the control of a direction control apparatus (not shown) isadapted to alternately connect said distributors to a land line 6.Corrector distributor rings 8 for station Aare shown with theirassociated brush 9, a corrector line relay 10 controlled by impulsesfrom station B over line 12. and an auxiliary corrector relay 14controlled from the corrector rings 8. The corrector mechanism 20 is forproducing angular shifts of the brushes traveling over the faces ofthe-correcting, transmitting and receiving distributor rings. Thiscorrector mechanism is located between the motor for driving thedistributors and the distributors themselves. The motor has not beenshown. The shaft 22 is driven by the motor and the shaft 23 drives thearms on which the brushes, such as'9, for the distributors are mounted.These arms are arranged to drive the brushes over the variousdistributor faces in a manner well known in the art. The correctormechanism 20 consists ot differential beveled gear arrangement. 25interposed between the motor shaft 22 and the brush shaft 23 and thegears that link these two shafts together are mounted on a supportingframe 27 secured to a worm pinion 28 that meshes with a worm 29. Anychange in the angular position of the worm pinion 28 changes the angularposition of the linking gears and this in turn changes the angularposition of the brush shaft 23 with respect to the motor shaft 22. Theworm 29 is rotatable to shift the angular osition of the worm pinion asmall angle y means of corrector magnets 31 and 32 in one direction orthe other. The ratchet wheel and pawl mechanisms 35 and 36,respectively, are operated by these magnets so that on the operation ofeither one of the magnets, an angular shift of the distributor brushesin one direction or the other is effective. In order to hold the worm 29firmly while the magnets are not rotating it, a separate ratchet wheel37 and a pawl 38 is provided. This wheel and pawl also limits themovement of the worm 29 to one step each time a corrector magnetoperates. The automatic corrector mechanism 20 is therefore capable olshifting the brushes of the distributors in a forward or in a backwarddirect-ion; magnet 31 being provided for shifting it in a forwarddirection and magnet 32 for shifting it in ay backward direction. Byforward is meant a shift in the same direction as the rotation of thebrushes; by backward is meant a shift oposite to the direction of therotation of the rushes. It is seen` therefore. that by this mechanism,corrections in either direction can be effected while the distributorbrushes are being rotated by the motor and hence synchronizing effectsmay be produced between the brushes of the distributors at differentstations as will be hereinafter more fully explained. A correctiondirection key 40 is provided to connect one corrector magnet or theother with the circuit controlled by the auxiliary corrector relay 14which in turn is under control of the corrector rings 8 and brush 9.

The equipment at the repeater station B comprises a receivingdistributor 100 and its associated storing relays 101 from which thesignals are retransmitted through the transmitting distributor 102 tothe submarine cable 103 leading to the terminal station C. Of thedirection control apparatus at this station only the cams 104, forcontrolling contacts to switch from reception to transmission and viceversa, have been shown. At this station signals received from line 6 arerepeated to cable 103 through the receiving distributor 100, storingrelays 101, transmitting distributor 102` While the signals from thesubmarine cable 103 are in synchronism with the distributors at stationA by means of a distributor arrangement 18 at station A whereby impulsesare sent over a .separate line 16 between these stations to the drivingmotor arrangement at station B.

The submarine cable 103 terminates at station C at which the equipmentfor receiving signals consists of the amplifier apparatus 300, linerelay 301, receiving distributor 302 and the printing apparatus 303. Thecorrection control relay 304 is in series with the line relay 301 tocontrol the corrector line relay 306 which in turn controls theapplication of correcting impulses through the corrector rings 310 Forthe actuation of the correcting mechanism 313 to correct thedistributors at this station forward during reception of signals at thisstation. This mechanism 313 is identical with the correspondingmechanism 20 at station A. and the magnet 314 is provided for forwardcorrection while the magnet 315 is rovided for backward correction. Thedlrection correction key is marked 310. Transmission from the station Cis directed from the impulse transmitting devices 320 through thetransmitting distributor 321 to the submarine cable 103 and thedirection control cam 322 causes the shifting of the cable 103Ytransmitted from the distributor segments 18 in Fig. 1 over theseparate synchronizing line 16 to the distributor motor 110 at stationB. Therefore stations A and B may be regarded as'a unit and station C asa separate unit bctwen which units synchronism must be maintained bymeans of signals transmitted over the cable 103.

The. knurled handle 350 is provided on the shaft 341 for manuallyadjusting the s vstem in order to set it to a synchronous condition.

Assuming that the initial syncl'irouous condition has been achieved andthat transmission is from stations A and B to station C, signal impulsesreceived over the cable 103 at station C are amplified in the amplifier300 and applied to a receivingr relay 301 and a synchronizing relay 304.Relay 304 responds to each reversal of the signal curlun Ill)

v335 or 345 associated therewith.

rent to reverse the position of its armature chronizing relay 306. Relay306 also reverses the position of its armature in response to eachreversal of current in its winding and successively charges condenser336, from a source of positive potential shown, and discharges itthrough the main ring 346 on a distributor 310, a brush 337 to segmentsAs long as the distributor at station C is in proper phase relation withrespect to the received Signals the brush 337 will be onone of thesegments 345 at the time relay 306 reverses the position of its armatureand the con- .denser 336 will be discharged through the negative batteryshown connected to segments 335 and no correction will be produced. 4Thedistributorl at station C, however, isset to run at a speed slightlylower than that of the distributor at station A.

Therefore the brush 337 will be constantly shifting back and eventuallywill be resting yon one ofthe segments 345 at the time relay 346reverses the) position of its armature. As a result of this the chargefrom condenser 336 will be applied through the brush 337 and a segment345 to the right hand winding of relay 339 and through the back contactand armature of ma net 314 to negative battery 'at key 316. Th1s causesthe armature of relay 339 to shift to the position opposite that shownin the drawing which applies positive battery over the armature of relay339 through the winding of magnet 314 to negative ybattery at key 316.This causes magnet y314 to operate and shift the distributor brushesforward through the differential gear mechanism comprising ratchet wheel340, worm 341, rand worm wheel 342.

` A correction takes place whenever brush 337 drops back far enough tocontact with a segment 345 at the time a signal reversal occurs andtherefore acts to maintain the distributor at station C at all times inphase with the received signals from stations A and B. I

- When transmission from A and B to C has continued for aprcdeterminedperiod,

the direction of transmission is reversed.

To switch the connections sothat sending can, take place from station Cto station A,

' the direction controlv cams 5, 104 and 322 are actuated by a timingdevice (not shown).

Thistiming device is merely a means for actuatlng the above mentionedcams at certain intervals to make them perform thisl cams atall threestations are controlled to perform their switching operationssubstantially simultaneously with due regard tolag The mechanism forconf in transmission. Cam 5 causes the contacts to open the connectionsbetween the sending distributor 1 and the line 6 and to close aconnection between the receiving distributor 3 and the line 6. Similarlythe cam 104 opens the connection to the receiving distributor 100 fromline 6 and closes a connectionv from line 6 to the armature of linerelay 106. One of the cams 104 also closes a circuit for the operationof relay 112 to open the connection between the submarine cable 103 andthe sending distributor 102 and close a connection between this cableand the amplifying device 105. Signals incom- .ing over cable 103 willtherefore now pass `as previously stated through the amplifying device105, line relay 106 and correction control relay 109. The operation ofcam 322 closes a circuit for the operation of relay 348 to cause thisrelay to actuate its armature to a position opposite to that shown inthe drawing. Hence, the connection between the cable 103 and theamplifying device 300 will be opened and a connection between the cableand the sending distributor 321 and transmitting device 320 closed. A

When the operations of the aforementioned cams are completed, signalswill be transmitted from the sending distributor 321 at station() overthe cable 103 through the receiving amplier 105 at station B and throughthe signal receiving relay 106 and the synchronizing relay 109. Relay109 thereupon repeats current reversals through the back contacts andarmatures of relay 113 over the conductors 12, the armatures and backcontacts of relay 42 of station A to relay 10 which functions in thesame manner as relay 306 at station C to apply synchronizing impulsesfrom a condenser to a synchronizing distributor 8. Since the distributorat station A normally runs slightly faster than the distributor -atstation C, the brushes at station A must be corrected backward, thisbein the converse of the operation at station and therefore switch 40 isset to actuate the backward correcting magnet 32. Relay 10 in operatingcloses a circuit for the operation of auxiliary corrector relay 14through brush 9, provided brush 9 has advanced out of synchronism withthe brushes of the sending distributor 321. If this is the case circuitswill be completed from one side of the condenser44, which previously hasbeen charged through the circuit completed at the right-hand contact andture of magnet 32 through negative battery to ground. This lattercircuit causes the auxiliary corrector relay 14 to actuate its armatureto a position opposite to that shown in the drawing. A circuit isthereby completed as follows: from battery, through the winding ofmagnet 32, left-hand closed contacts ot direction key 40, armature andcontact of the auxiliary corrector relay 14 to ground. Magnet 32 inoperating actuates the pawl and ratchet mechanism 36 to shift throughthe corrector mechanism 20 the Shaft 23 for a small angulardistance ina. backward direction in relation to the rotation ot' the shafts 22 and23. On the operation ot' magnet 32 the circuit through the right-handwinding of auxiliary corrector re ay 14 is. opened at the armature andback contact of magnet 32 and a circuit for the left-hand winding ofrelay 14 is closed from battery at the armature and frontl Contact ofmagnet 32 through the left-hand winding of relay 14 to ground. Thiscircuit restores the auxiliary corrector magnet 14 to its normalposition and consequently the circuit for the stepping magnet 32 isopened so that this magnet returns its armature to normal condition.Corrections of this kind will occur until the brushes of the receivingdistributor 3 arein perfect synchronism with the brushes of the sendingdistributor 321.

Although the apparatus, the operation of which is set forth above, iscapable of maintaining synchronism between stations A and C duringtransmission in one direction, it has been found that the stations mayfall out of synchronism during the reversal of the direction oftransmission and the reason for this can best be explained withreference to Fig. 4 of the drawings in which a diagrammatic presentationhas been made of various distributor segments and impulse curves andtheir inter-relations in order that an exact understanding of the effectof the phasing and orienting operations relating to this finaladjustment may be had from this diagram.

First, it will be assumed that the motors at stations A and C arerunning at exactly the same speed. Therefore, so far as the motor speedis concerned no corrections will he required after synchronism has oncebeen obtained. rl`his assumption can. of course, not, be attained inactual practice and is, therefore. only justifiable on the. ground that.it simplifies the following descriptions relating to the necessity forthe orientahility of the correcting ring 8. In this diagram it has beenassumed that the brushes travel from left. to right as indicated by thearrow. As previously stated a correction cauouly take place at theinstant a new impulse or signal is actuating a corrector control relay,such as 304 or 109, and then only if the impulse occurs when a brush,such as 337,

is on a correcting segment, for example 345 and the new impulse is ofthe opposite polar ity to that of the receding one. The correctingsegments 1n Fig. 4 are hereafter called black segments.

It the condition of sending from station A is considered, reference maynow be had to the sending segments of the sending distributor 1 shown at400. The sending brush 401 sweeps from left to right over the sendingsegments 400 and impulses, such as 402, will therefore be sent tostation C. These impulses are for the sake of convenience assumed toconsist of successive impulses of opposite. polarity, although iu actualpractice they may consist of a plurality of impulses of one polarityfollowed by a plurality of impulses ot the opposite polarity. An impulseinterval is represented as occupying space or time, that is, a segmentswept over by the brush 401 or the time required for such movement.

At station C the received impulses 405 come in later in time due to thelag in transmission. As is well known this lag is due to thetransmission characteristics of the several circuit elements, such forexample, as the line 6, submarine cable 103. amplifier 300, relay 301,etc. It is assumed that the system has already been phased or lined upto compensate for this lag. Hence it follows that when brush 401 is atthe center of the sending segment as shown at 401', brush 406 has notyet reached the center of the receiving segment, but will reach it at atime later (equal to the line lag) when the center of the signal impulsearrives. The receiving segments are made shorter than the sendingsegments in order that the, central portion of the received signal willbe effective for operating the printing relay. Corrector brush 408 isshown in line with receiving brush 406, but in practice it should beunderstood that the receiving brush may be oriented without disturbingthe 'corrector brush. As stated above, the receiving segments 407 havebeen phased to receive approximately the middle of the signal impulses405-and the corrector rings 409 have such a relation to the point of thebeginning of the impulses 405 that no corrections will occur as theseimpulses begin because the corrector brush 40S is ou the left hand endof a non-correcting,r segment of the group 405). The uou-correetiugsegments are hereinafter called white segments.

When the direction of transmission changes to transmit from station C tostation A the sending rings 410 of distributor 321 come into play. Asfar as the transmission of impulses is concerned the, sending rings 410may at this time have any relationship whatever to the receiving andcorrecting rings 407 and 409. As the sending brush 411 sweeps over thesending seg- `ments 410 impulsesl such as 412 are sent out over thecable to station A.

The received impulsos 413 come in at station A with an assumed line lagof half the distance between the beginning of two succeeding impulsessent out from station C. Since it is assumed that the system is alsoalready phased or lined up for reception of impulses in this direction,it follows that when the brush 411 travels from the beginning of asending segment of ring 410 as shown in the drawing the receiving brush414 will arrive at the positions shown in the drawing when the lmpulse413 arrives. Here also the receiving segments 415 are shortened andphased to receive only the middle portion of the impulses. The correctorbrush 416, (same as corrector brush 9 in Fig. 1) and the corrector rings417 (same as corrector rings 8 in Fig. 1), if they are properly orientedwith respect to the sending ring 400 and sending brush 401, will havesuch relation to the beginning of impulses 413 that no correction willoccur as the beginning of impulses take place because brush 416 will beat the right hand end of a white segment.

Assumin now that another reversal of direction o transmission occurs sothat stationA again transmits to station C, the relative yrelationshipbetween correcting segments 417 and the sending segments 400 is ofimportance. If, as we have assumed, the correcting segments 417 areproperly set, no correction resulted at station A when the direction oftransmission was first reversed. Hence, the distributors at bothstations are in their original relative positions and when the directionof transmission is next reversed and station A again sends to station C,the distributors at thetwo stations are still in proper phase relation.

But suppose that, following the first reversal, the correcting segments417 were not properly set with respect to the sending segi ments 400.Suppose that the correcting brush 416 were on the right end of a blackor correcting segment instead of the right end of a white segment whereit should have been.- The correcting mechanism at sta,- tion A wasthereupon actuated to correct all the brushes at station A backward thewidth of a correcting segment (which is half the width of a sendingsegment). This displaced the sending brush 401 to the position 401(assuming that it was formerly at position 4012). Therefore, whenstation A again transmits, the first impulse w1ll be transmitted fromstation A and received at q f station C at a corresponding portion oftime later thanthe previous time. That is, the position of the impulsesfrom station A in their relation in time to impulses 402 is indicatedwith a dotted impulse curve 420 and the arrival of the impulses atstat-ion C in this relationy in time to impulses 405 is indicated bydotted impulse curve 421. Under these new conditions the first impulsewould be received on the first receiving segment of ring 407 and thesecond impulse would also come on the first receiving segment and thesystem would be out of line. 1t will be noted that the system wouldremain out of line as the beginning of the impulses would take placewhile the correcting brush 408 travels over a white segment of ring 409.This may be verified by the d otted vertical line projected from thebeginning of an impulse 421 to a white seg ment of ring 409.

We have considered above the result of the correcting brush beingdisplaced the width of the correcting segment in one direction.Obviously, if the displacementis greater in the same direction or lessthan a segment and iu the opposite direction, the brush 416 will fall ona dknon-correcting or white segment and no correction will result. Thiswould do no harm in our hyp0- thetical case with the distributors atstations A and B running at the same speed, but 1n practice, with thedistributors runnin at different speeds, they would soon drift apart.

From the foregoing considerations it can be seen that the system may getout of synchronism even though the motors at the two stations arerunning at exactly the same speed. In the actual system of correctionemployed the motor at station A is running faster than the motor atstation C. This requires a forward correction of the brushes at stationC in the manner previously described to maintain synchronism Whilestation A is sending, and a backward correction of the brushes atstation A when station C is sending. Therefore, during the change overor switching period when no impulses are transmitted over the cable andconsequently no correction can take place the brushes at station A gainin speed andthe brushes at station C lose in speed so that whentransmission again begins a few correcting steps are normally requiredto bring the system back into synchronism.

In the practical operation of the system the proper orientation of thering 417 may be determined by observing the number of corrections thattake place to bring the system toward synchronism at the receivingstation after a reversal of direction of transmission has occurred. Ifthe number of steps which occur are just the number re- 401 during achangeover interval, then the orientation of the ring segments 417 iscor rect. If it is different, the roper orientation change can bedetermined, from the amount of the difference, from the fact that uiredto correct for gain or loss of brushl the number is greater or less thanit should be and from the further fact that the distributors do or donot get out of. phase on successive transmissions in the same direction.It is evident then that as previously explained the synchronizing of thebrushes at the two stations is dependent on the proper orientation otthe corrector rings 417, taking into account the difference in speed ofthe motors at the tivo stations, the fact that no correction takes placeduring the changeover period and the relationship of the sending ring400 to the corrector ring 417.

Since alternate segments of the corrector rings are similar and areconnected together as shown at 8 in Fig. l and at 310 in Fig. 3, it isunnecessary to make the correcting ring adjustable through acircumferential distance greater than that between successive correctingsegments.

IVhat is claimed is:

1. In a synchronous telegraph system, a plurality of stations,distributors at .said st ations, a transmission line connecting saidstations, means for automatically reversing the direction oftransmission from time to time, synchronizing means for saiddistributors controlled by the distributors at the station which issending, means for chang ing the relative positions of the sendingsegments and the correcting segments at one of said stations whereby thesystem may be adjusted to maintain synchronism during successivereversals of the direction of transmission.

2. In a synchronous telegraph system, a plurality of stations, sendingand receiving distributors at each station, a correcting distributor ateach station, a transmission line connecting said stations, means forautomatically reversing tbe direction of transmission from time to time,synchronizing means for said distributors comprising means at eachstation for synchronizing distributors at the station receiving with adistributor at the station sending including the correcting distributorat the station receiving, and means for changing the relative positionsof the sending distributor and the correcting distributor at one stationto maintain synchronism between the distributor at said stations duringsuccessive reversals of the direction of transmission.

3. In a. synchronous telegraph system, a

plurality of stations, sending and receiving distributors at eachstation, a correcting distributor at each station, a transmission lineconnecting said stations, means for automatically reversing thedirection of transmission from time to time, synchronizing means forsaid distributors comprising means at each station for synchronizingdistributors at the station receiving with a distributor at the stationsending including the correcting distributor at the station receiving,and means for Vchanging the position of the correcting distributor withrelation to the sending distributor at one station by at least thedistance of one sending segment for maintaining synchronism between thedistributors ot' said station during successivo reversals of thedirection of transmission.

4. 1n a synchronous telegraph system, two stations, sending, receivingand correcting distributors at each station, a transmission lineconnecting said stations, means for automatically reversing thedirection of transmission at pi'edetermined regular intervals,synchronizing means ior the brushes on said distributor comprisingautomatic means for synchronizing the brushes of one station with aspeed at the other station characterized in this, that the s eed of thebrushes of the distributors of tie receiving station is svnchronized tothe speed of the brushes ol the distributors of the sending station in asystem where the normal speed of the brushes of one station is fasterthan the normal speed of the brushes at the other station, and means fororientating the distributor at one station to a certain relation to theposition of the sending distributor at this station whereby thesynchronizing means is controlled to reestablish synchronism betweentlie brushes of the distributors at the two stations it' the brushes getout of synehronism during the successive reversals of direction oftransmission due to the diier ence in speed of the brushes at the twostations and to correct the tendency of the brushes to get outY ot` svnchronism during thel successive reversals of direction of transmissiondue to certain relationship of the brushes of the sending and correctingdistributors and the brushes of the receiving distributor of said otherstation.

In witness whereof, I hereunto subscribe my name that 25th day of June,A. D., 1926.

GEORGE A. LOCKE.

